The present invention relates to a passive/active fluid exercise device. More particularly, the invention relates to a passive/active fluid exercise device which includes computerized control of fluid flow through a fluid system, and includes force (resistance) and movement sensors.
For purposes of this disclose, the term fluid is intended to include hydraulic fluid as well as pneumatic fluid.
Exercise devices of the type having a variety of controls, sensors, and hydraulic or pneumatic arrangements, are known in the prior art.
U.S. Pat. No. 4,722,525 to Brentham discloses a physical fitness testing apparatus which includes a hydraulic exercise device. The apparatus includes transducers for determining force applied by the user and selector valves connected to double acting cylinders to provide resistance in opposite directions.
U.S. Pat. No. 5,230,672 to Brown et al. discloses a computerized exercise apparatus which includes a load cell. The load cell is used in conjunction with hydraulic pistons to control tension and provide feedback to the user of the equipment.
U.S. Pat. No. 5,314,390 discloses a programmable exerciser wherein a motor is provided. The motor is used to perform iso-acceleration and iso-deceleration exercises, and has a limb move mode for assisting users.
U.S. Pat. No. 5,011,142 to Eckler teaches an exercise control system which includes a closed hydraulic circuit. The closed hydraulic circuit is used to provide positive and negative iso-dynamic resistance, and a combination of rotary and linear cylinders is used to control torque ratios.
U.S. Pat. No. 5,356,353 to Takaoka relates to exercise devices having monitoring and control of the range of motion.
U.S. Pat. No. 5,209,715 to Walker et al. teaches an automatic force generating and control system, for use in exercise equipment.
U.S. Pat. No. 4,919,418 to Miller teaches exercise equipment having a computerized drive mechanism for exercise, physical therapy, and rehabilitation.
U.S. Pat. No. 4,846,466 to Stima teaches microprocessor controlled exercise equipment having an electro-hydraulic exercise system.
U.S. Pat. No. 4,544,154 to Ariel teaches exercise equipment which includes a passive programmable resistance device.
From the foregoing, it is seen that it is a problem in the art to provide a device meeting the above requirements. According to the present invention, a device is provided which meets the aforementioned requirements and needs in the prior art. Specifically, the device according to the present invention provides a passive/active fluid exercise device which can be selectively placed in either a passive mode or an active mode, and wherein in the passive mode the system can provide a resistance type of operation, and an active mode can provide a velocity type of operation.
The different modes of operation are fully controlled by the computer software, for example. The passive system includes a push and pull mode. In this mode, a pump can be off or on during idling. Also in this mode, a solenoid valve is energized to an xe2x80x9copenxe2x80x9d position. A servo valve sets a resistance, or restriction, for the fluid flow in the system. As an exercise bar is pulled down, fluid is forced out of a rod end of a fluid cylinder, and at the same time, fluid is drawn into a cap end of the cylinder.
The actual resistance in the system is generated and controlled by the servo valve. In order to provide a true measure of the resistance, fluid entering the cap end of the cylinder is allowed access through a low pressure check valve which keeps any residual back pressure, or vacuum, to an absolute minimum. This check valve also compensates for the differential areas of the cylinder, simplifying the hardware arrangement.
The active mode is useful for physical therapy applications. In this mode of operation, the system is pre-configured to provide a constant cycling operation at absolute minimum force levels. This is accomplished in two ways. First, the load cell senses the actual force generated by the subject. Second, the position feedback senses actual movement of the exercise bar. As long as the subject is providing enough force to move the exercise bar, the feedback device confirms movement to the computer which will adjust the resistance which is set by the electronic pressure control valve, to a value which will allow the subject to continue moving the exercise bar. This force is measured by the load cell and controlled by the servo-valve.
Other objects and advantages of the present invention will be more readily apparent from the following detailed description when read in conjunction with the accompanying drawings.